The order, which extends the so-called “national emergency” against the regime for a year, authorising economic restrictions against it, isn’t unexpected – but appears to contradict Mr Trump’s previous tweet saying: “there is no longer a Nuclear Threat from North Korea” following his summit with Kim Jong Un in Singapore.

The executive order states that “the existence and risk of proliferation of weapons-usable fissile material” and the actions and policies of the North Korean government “continue to pose an unusual and extraordinary threat to the national security, foreign policy, and economy of the United States”.

Mr Trump claimed at a Cabinet meeting on Thursday that denuclearisation had already begun but there is reportedly no evidence to suggest that this is correct.

On Friday evening the Pentagon said it has “indefinitely suspended” a major military exercise with South Korea, known as Freedom Guard and scheduled for August, as well as two Korean Marine exchange training exercises.

A Pentagon spokeswoman said further decisions about military exercises in South Korea “in support of diplomatic negotiations” led by Secretary of State Mike Pompeo will depend on North Korea “continuing to have productive negotiations in good faith”.